The present invention relates to a semiconductor device and a control method of the same.
A crystal oscillator is widely used to generate a reference frequency signal in, for example, a semiconductor device for wireless communication. The crystal oscillator includes a crystal resonator and an oscillation circuit that oscillates the crystal resonator.
An oscillation frequency of the crystal resonator has a slight temperature dependence, and an oscillation frequency of a normal AT-cut crystal resonator varies in a cubic curve with respect to temperature. As an example, in a temperature range of −40 to 85° C., the oscillation frequency has a frequency deviation of about ±20 to 30 ppm.
Japanese Unexamined Patent Application Publication Nos. 2008-300978 and 2013-098860 disclose a temperature compensated crystal oscillator (TCXO) including a temperature compensation circuit that performs control so as to cancel the temperature dependence in a cubic curve described above and maintain the oscillation frequency constant. The temperature compensated crystal oscillator can reduce the frequency deviation to, for example, ±1 ppm or less.